The invention is directed to a process for the production of 3-cyanopyridine by catalytic reaction of 3-methylpyridine with ammonia and oxygen at elevated temperature. It is particularly directed to catalysts for this purpose made of compounds of the elements antimony, vanadium, and oxygen and at least one of the elements iron, copper, titanium, cobalt, manganese, and nickel, as well as the process for producing the catalysts.
There are known several processes for the production of 3-cyanopyridine from 3-methylpyridine through its reaction with ammonia and oxygen at elevated temperature in the gas phase. They differ through the reaction conditions and especially through the catalysts. Among the processes and catalysts only those are suitable for use on an industrial scale which show good selectivity and simultaneously result in high space-time-yields.
It is known to use as catalysts for the reaction of alkylpyridines to cyanopyridines tin phosphate with addition of compounds of the elements molybdenum, bismuth, vanadium, iron, or cobalt (German AS No. 1770841). This process in the case of the reaction of 3-methylpyridine to 3-cyanopyridine only results in moderate yields, moreover, at slight selectivity.
Besides it is known to employ as catalysts tin vanadate in admixture with diphosphorus pentoxide on aluminum oxide, silica gel or their mixture (Japan published 42-6066) or molybdenum oxide in admixture with oxides of vanadium, chromium, manganese, or cobalt on aluminum oxide, magnesium oxide, silicon oxide, or titanium oxide (Japan published No. 45-13572) or pure divanadium pentoxide of specific surface area and particle size (German OS No. 2435344). These processes, it is true result in relatively favorable yields at good selectivity but they require reaction gases which are greatly diluted with air. Therefore, there are obtained only small space-time-yields.
Furthermore, it is known to use catalysts which are produced from mixtures which contain antimony and vanadium in the atomic ratio of from 1.1:1 to 50:1 and at least one of the elements iron, copper, titanium, cobalt, manganese, and nickel and in a given case a carrier material and are prepared by heating to a temperature of 600.degree. to 1100.degree. C. in the presence of oxygen (German Pat. No. 2039497) and related Lussling U.S. Pat. No. 3,923,819, the entire disclosure of which is hereby incorporated by reference and relied upon. It is true that in this manner high space-time-yields are produced, however, the selectivity of the catalyst is unsatisfactory.